The drag of air leads to energy losses that increase exponentially with increasing speed of a flying object. Furthermore, the drag leads to mechanical loads and stresses acting upon the constructive elements of the flying object. These loads and stresses have to be considered when dimensioning the flying object. Accordingly, the drag influences the minimal dimension of the constructive elements. However, increased dimensions due to the acting loads and stresses lead to an increased consumption of the energy source of the propulsion when changing or maintaining the speed of the aircraft. Additionally, under certain conditions the increased drag could reduce the payload of the flying object. Investigations have shown that a change of the total drag of 1% may correlate to a change of the payload of approximately 5 to 10% in a modern commercial aircraft, cp.    [1]. D. Bushnell, Supersonic Aircraft Drag Reduction, AIAA Paper 90–1596, June 1990[1].
Document [1], which is incorporated entirely herein by reference, contains an overview on common technologies for reducing the drag of an aircraft.
Due to an exponential dependence of the drag on the flight speed for supersonic flying object a reduction of the total drag of 1% leads to a further increase of the payload.
Usually the outer shape of wings located in the airflow is the result of an optimization depending on a lot of different requirements. One such requirement is that the wing has to provide high performance throughout a large range of speeds. The aforementioned requirement is commonly fulfilled for wings used for transonic or supersonic aircrafts by variable sweep wings (swing-wings) or by providing cranked delta planform. Both these applications may lead to a low wave drag for a use of the wing during cruise speeds as well as a sufficient lift force during take-off and landing.
In a lot of cases the basic aerodynamic design of the wings is determined by means of theoretical or numerical models requiring wings of different known types of basic designs, cp. [1]. Examples for such simple shapes of wings are those being describable by means of a two-dimensional analysis.    [2] Bertin J. & Smith M., Aerodynamics for Engineers, Prentice-Hall, 1979, 410 p. [2], which is incorporated entirely herein by reference, contains an overview concerning the knowledge for the reduction of the drag for planar wings.